Will a Stuffed Animal Survive Free Fall from the Earth’s Stratosphere?
At the end of a busy day yesterday with four interviews and a two-hour podcast with Brian Keating (posted here), I received a phone call from the New-York Post reporter David Spector, who asked me a simple question: “Will a stuffed animal survive free fall to the ground from the Earth’s stratosphere?”
I took a pen and paper and within a few minutes derived the answer in following one-page note, accompanied by my email:
“Dear David,
I just derived a handwritten note that explains everything. A photo of it is attached below. Feel free to feature this image in your article because it derives the relevant numbers.
Here is the explanatory text: an object released from rest in the stratosphere in the absence of any wind will reach a terminal speed at which its friction force on air balances its gravitational force towards Earth. This terminal speed scales as the square root of the product of the mass density of the object with its size.
For a rain drop of a millimeter size, this terminal speed is about 3 meters per second whereas for a stuffed animal with a 10-centimeter size, the terminal speed would be about ten times larger if it is soaked in water and has a similar mass density. However, even at this maximum speed, 30 meters per second, the stuffed animal can survive the journey. This speed is ten times smaller than the sound speed. As a result of this subsonic motion, no shock wave will be generated in the surrounding air and any heat dissipated from the friction of the stuffed animal on air will not destroy it.
Meteors of the same size as the stuffed animal burn up in the Earth’s atmosphere because they collide with Earth’s atmosphere at an initial speed of several tens of kilometers per second. Such a speed is a thousand times larger than that of the stuffed animal dropped from the stratosphere, dissipating up to a million times more energy in heat as the air slows them down. This vastly larger energy release generates a fireball bounded by blast wave around them that burns them up. Since they move two orders of magnitude faster than sound, the huge pressure wave that their energy release generates, is bounded by a blast wave.
___________
The stratosphere is not considered empty space because it represents the second major layer of the Earth’s atmosphere.
Let me know if I can be of additional help.
Avi”
The title of my MSc thesis, which preceded by a year my PhD thesis at age 24 — exactly forty years ago, was: “Analytical Models for the Evolution of Strong Shock Waves Generated by High Irradiance Lasers in Solids and Fast Spark Discharges.” Three days ago, I gave the weekly colloquium in the department of Physics and Astronomy of Notre Dame University in Indiana, where my host — Professor Grant Mathews — reminisced about his time at Lawrence Livermore National Laboratory, where he helped motivate the National Ignition Facility which employs the interaction of a powerful laser beam with solid targets to simulate the physics of nuclear explosions in the atmosphere.
Physics from basic principles works. The analytical model that I developed during my MSc thesis helped design an experimental system that was subsequently increased by a factor of a hundred in length and followed exactly the scaling laws that my model predicted.
Some people consider science fiction as fun, but I find science without fiction as much more fun because it described the physical reality we all share. Magical thinking might be fun for a short while but then it is doomed to die if it disagrees with the physical reality that we live in.
We must keep this important lesson in mind when interpreting any data released by the U.S. Government on the new domain of aliens.gov (which is not alive as a website yet, as reported here).
***
My answer was based on a traditional approach of a handwritten note dictated by natural intelligence. But what answer would an artificial intelligence (AI) system give? I asked Grok the same question and requested “Think Harder”. After a few minutes, similar to the amount of time that it took me to write my note, I received the following answer:
“Yes, a stuffed animal can (and has) survived free fall from the stratosphere. A real-world example proves it: in November 2025, Bradfield Bear (a small teddy in school uniform) was launched by students at Walhampton School in the UK with the Southampton University Spaceflight Society. It reached ~27 km (16.7 miles) in the stratosphere, detached due to turbulence, and free-fell without a parachute. The school launched a public search (tracking data pointed to the Henley-on-Thames/Reading area), with teachers reassuring students that “he is very brave and resourceful” and did “amazingly.” No reports indicate destruction on impact — it’s simply missing and presumed intact enough to be spotted.
Why Physics Guarantees Survival: In the thin upper stratosphere (~27 km), air density is extremely low, so the bear accelerates quickly under gravity (potentially hundreds of km/h initially). But as it descends into denser air, drag force (proportional to velocity squared) rapidly increases until it equals weight — reaching terminal velocity, a constant low speed. For a typical fluffy stuffed animal (~0.4 kg mass):
High drag coefficient (Cd ≈ 1.8) + large effective area (~0.2 m²) + low density = very slow terminal velocity.
Calculated: ≈ 4.2 m/s (15 km/h or 9 mph) — gentler than dropping from a second-story window! Even a more compact version is only ~11 m/s (41 km/h).
This is far below a human skydiver’s ~190 km/h or a dense object’s destructive speeds. The bear decelerates gradually, experiences low G-forces, and hits the ground softly (especially on grass/soil). Cold (-50°C+) and low pressure at altitude may temporarily stiffen fabric but don’t destroy it.
Real landing: On soft ground, it may get dirty or slightly torn but remains recognizable. Hard surfaces or high winds increase risk, but plush toys routinely survive these amateur “near-space” drops.
Variables and Tips: With parachute (standard in most balloon payloads): nearly 100% survival. Pure free fall: still fine for lightweight fluffies, as Bradfield Bear demonstrates.
Historical note: Many student projects (2013 “Babbage” bear from 39 km, 2017 UK teddies to 30 km+) return battered but whole.
These experiments are popular STEM projects — add a GPS tracker, GoPro, and parachute for guaranteed recovery and epic footage. Bradfield Bear’s adventure captured global attention; if you spot him, the school is still looking! In short, yes — physics and real footage confirm stuffed animals are tough enough for the stratosphere.”
***
Call me old-fashioned, but I still prefer the content of a handwritten note dictated by natural intelligence over AI.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
